In several diesel engines today, fluid control valves regulate the flow of actuation fluid to and from hydraulic devices, including but not limited to fuel injectors. Depending on the positioning of a valve member, the fluid control valve either connects the fuel injector to a source of high pressure actuation fluid causing the fuel injector to activate, or connects the fuel injector to a low pressure actuation reservoir causing the fuel injector to deactivate, reset itself, or remain inactive. Typically, the movement of the valve member is controlled by at least one solenoid actuator. For instance, hydraulically actuated fuel injectors, such as that shown in U.S. Pat. No. 6,161,770 issued to Sturman on Dec. 19, 2000, include a solenoid driven fluid control valve that is attached to an injector body.
The Sturman fluid control valve includes a spool valve member that doubles as an armature. The armature is moveably positioned between a first solenoid actuator and a second solenoid actuator. Each solenoid actuator includes a solenoid coil mounted in a stator comprised of a relatively soft, magnetic material that aids in controlling the direction of the magnetic flux caused by the energized solenoid coil. Further, the armature/valve member is also comprised of a relatively soft, magnetic material that will be attracted to the energized solenoid coil. When the first solenoid coil is energized, the armature/valve member is attracted to and pulled in the direction of the first solenoid coil. Because the armature is included as part of the valve member, the valve member also moves in the direction of the energized solenoid coil. The armature/valve member stops when it impacts with stop surface on the first stator. When the second solenoid coil is energized, the armature, and thus the valve member, are pulled in the direction of the second solenoid actuator. The armature stops when it impacts with a stop surface on the second stator. Thus, when the armature is pulled toward the energized solenoid coil, regardless of whether the energized solenoid coil is the first or second solenoid coil, a stop surface of the armature/valve member impacts a stop surface of one of the stators. Thus, the relatively soft, magnetic materials comprising the stator and the armature will be subjected to repeated impacts, which may lead to undesirable wear and decrease the durability of the solenoid actuators and undermine the functioning and/or predictability of the valve.
The present invention is directed to overcoming one or more of the problems as set forth above.